What Do You Use For A Vapor Barrier?

[spam4us]

What Do You Use For A Vapor Barrier?
Anything special?
Will any type of plastic sheet work?
How thick (mills)?

Is taping the seams necessary or just staple where 2 sheets meet?
This will be for interior OSB walls and metal ceiling. Northeast US.

Thanks

 

[matt_i]

6mil would be minimum. 10 mil if you intend it to work as designed, in my opinion.

The 6mil will get damaged walking over the aggregate during all of the prep and pour and show little holes all over. The 10 is much more resistant to this and won't have the holes.

I lapped the sheets, no tape, I think 18 inches. I had a rebar grid to hold down the plastic. If wind will be catching it then I'd use enough tape not to have to do it over again.

 

[ant.foste]

6mil would be minimum. 10 mil if you intend it to work as designed, in my opinion.

The 6mil will get damaged walking over the aggregate during all of the prep and pour and show little holes all over. The 10 is much more resistant to this and won't have the holes.

I lapped the sheets, no tape, I think 18 inches. I had a rebar grid to hold down the plastic. If wind will be catching it then I'd use enough tape not to have to do it over again.

The OP seems to be asking about housewrap, not underslab.

 

[dfiler2]

6 mill is what we always use on interior walls and ceilings, assuming that's the question.

 

[K'ledgeBldr]

6mil is quite common...

For a good understanding of what vapor barriers/retarders actually do, mean, and function with other materials- have a read:

https://www.certainteed.com/insulation/vapor-retarders-and-moisture-management/

 

[Leaflessshadetree]

6 mil is common. I usually use 10 mil and keep tape around to seal any oopses.

 

[spam4us]

Thanks for all the replies.

I am asking about the vapor barrier(not housewrap, not under a slab) that you put on walls and ceilings and then it gets covered with drywall/osb/metal.

I have already insulated the pole building and the insulation is unfaced.
Thanks

 

[OCD]

6 mil Vapor Barrier for the walls, Acoustic Sealant on the top and bottom edges and any poly seams, staples, then tuck tape over the edges and seams too... I even tuck tape over the staples... Lol!!

 

[K'ledgeBldr]

Thanks for all the replies.

I am asking about the vapor barrier(not housewrap, not under a slab) that you put on walls and ceilings and then it gets covered with drywall/osb/metal.

I have already insulated the pole building and the insulation is unfaced.
Thanks

Yep; we got it. 6mil poly!
And yes, when using a "vapor barrier" like 6mil poly you don't want faced batt insulation. A doubled vapor barrier/retarder can trap moisture inside the wall- No Bueno!

 

[ArcticGabe]

You may want to take a look at the link in this post. Another member posted a good article about vapor barriers, and what to use depending on your climate.

https://www.garagejournal.com/forum/showpost.php?p=8040795&postcount=3

 

[DC73]

A doubled vapor barrier/retarder can trap moisture inside the wall- No Bueno!

Agree. No Bueno. The exterior sheathing and siding are important too as if they are too much of a vapor barrier when installing an interior barrier, you set yourself up for a moisture sandwich. The bottom line is that if moisture gets inside a wall, the wall needs to be able to dry to one side at least.

You may want to take a look at the link in this post. Another member posted a good article about vapor barriers, and what to use depending on your climate.

https://www.garagejournal.com/forum/showpost.php?p=8040795&postcount=3

Good article but needs to be updated a bit. Building scientists are getting away from recommending true vapor barriers except in special circumstances like indoor swimming pools. Instead they are recommending vapor retarders and more specifically they are recommending smart membranes. What's best is very climate specific. Would recommend more reading on BuildingScience.com and GreenBuildingAdvisor.com. The Q&A forum on GBA is a good place to post questions for more specific information.

DC